He is the only bowler of recent times apart from Ajantha Mendis of Srilanka to bowl the carrom ball.[3] He has been India's highest wicket taker since his debut with 245 wickets in all forms of the game. He is also a very handy lower-order batsman and has scored two centuries and three half-centuries in his Test career so far.

Ashwin made his ODI debut for India against Sri Lanka in June 2010. Later, he was selected to represent the Indian team which won the 2011 Cricket World Cup. He made his World Cup debut in March 2011 against the West Indies with bowling figures of 10–0–41–2. He played his second world cup match against Australia in the second quarter final at Sardar Patel Stadium and finished with figures of 10–1–52–2.

In November 2011, he made his Test debut earning his test cap from Sachin Tendulkar against West Indies.In the third Test, he scored his maiden international century, helping India to a draw. Ashwin was awarded the Man of the series for his performances with both ball and bat. Ashwin subsequently toured Australia for India's four-Test series in 2011/12. He played in three tests taking nine wickets at an average of 62.77.

Ashwin took 18 wickets at average of 13.11 in two test matches against New Zealand and become Man of the Series. In the 1st Test, he returned match figures of 12/85 bettering Venkataraghavan 12/152 for the best figures by an Indian spinner against the kiwis. He achieved his career best test ranking of 18 after the series against New Zealand and 9th in the all-rounder rankings.

In the England tour of India in 2012, he took 3/80 in the 1st innings in the 1st test at Sardar Patel Stadium to become the fastest Indian to record 50 wickets in Test matches as he overhauled the milestone in his ninth game. In December 2012, Ashwin completed 500 runs in his 11th Test cricket match. With this, he shares the record of becoming the fastest player along with Australia’s Jack Gregory and England’s Ian Botham, who also took 11 Tests to reach the mark of completing the all-round double of 500 runs and 50 wickets. He finished the series with a tally of 29 wickets and won the Man of the Series award. Ashwin became the 3rd Indian off-spinner to take 25-plus wickets in a series after Harbhajan Singh and EAS Prasanna.

Ashwin was part of the Indian team that won the 2013 ICC Champions Trophy where took 8 wickets from 5 matches. Ashwin surpassed former India captain Anil Kumble as the highest wicket-taker for India in a four-Test series when he claimed his 28th scalp in the Border-Gavaskar Trophy in 2012/13 at the Feroz Shah Kotla in Delhi. Ashwin scored a hundred and took nine wickets when India played against West Indies at the Wankhede Stadium in 2011. Only four other India players have hit a hundred and taken five or more wickets for the match. Ashwin is the only one to do it twice. The 280-run partnership between Rohit Sharma and Ashwin was India's highest in Tests for the seventh wicket, beating the unbeaten 259-run partnership between VVS Laxman and MS Dhoni against South Africa at the same venue in 2010. This was also the second-highest partnership for India against West Indies for any wicket in Tests.

In 2013-14 season, after a poor performance against South Africa in the 1st Test in India's tour of South Africa 2013–14, Ashwin was dropped for the 2nd test and didn't play in any of the tests on the New Zealand tour. He was part of the Indian team that competed in the 2014 Asia Cup and took 9 wickets from 4 matches finishing as the joint 3rd highest wicket taker in the tournament where India failed to reach the finals. Later, Ashwin was part of the Indian team that reached the finals of 2014 ICC World Twenty20. He was the tournament's joint second highest wicket taker with 11 scalps.

Ashwin is a tall off-spinner who primarily relies on the bounce of the pitch to get his wickets. He produces a lot of variations of the ball and flights the ball thereby giving it more chance to spin and dip on the batsman. In addition to his normal off-breaks, he produces an arm ball and the carrom ball, the latter of which he uses frequently in the shorter formats. In IPL 2013, he bowled leg-breaks and googly as well.[7] However, in an interview, he has stated that he refrains from bowling the doosra as it requires him to bend and straighten his arm which he finds difficult to do.[8]

Ashwin became the fastest Indian bowler to reach 100 test wickets as he got to the milestone in his 18th Test match. The previous record holder was legendary Indian spinner Erapalli Prasanna who got there in his 20th test. Ashwin also became the 5th fastest bowler in the world to reach 100 Test wickets after G Lohmann (Eng in 16 matches), CTB Turner (Aus in 17 matches), S F Barnes (Eng in 17 matches) and C Grimmett (Aus in 17 matches). Ashwin became the first Indian cricketer to score a century and take five wickets in same test match on 2 separate instances.[9] He achieved this double for the first time in his third Test against West Indies in 2011 when he made 103 and took 5/156 in the first innings. He repeated the same feat in the Kolkata test against West Indies in November 2013 where he took 2/52 in the 1st innings and 3/46 in the 2nd innings and scored 124 in India's 1st innings. Other Indians to have done this once are Vinoo Mankad in 1952 and Polly Umrigar in 1962. This feat had only been achieved 26 times previously in world cricket, the last occasion being by Jacques Kallis in 2002.

Ashwin is also the third Indian cricketer to be awarded the Man of the Match (MoM) on debut. Other Indians to have done this before him were Narendra Hirwani, Pravin Amre, R.P. Singh. Rohit Sharma and Shikhar Dhawan achieved this feat after Ashwin. Ashwin registered the 2nd best bowling on debut by an Indian bowler with 9/128, behind Hirwani’s 16-wicket world record debut performance. Ashwin became the fastest Indian to record 50 wickets in Test matches as he overhauled the milestone in his ninth game. He achieved it when he dismissed the England opener Nick Compton on 16 November 2012 during the second day of the first Test at Ahmedabad. The previous record holder was the legendary Anil Kumble, who had reached the milestone in his tenth Test. On 8 December 2012, Ashwin completed 500 runs in his 11th Test cricket match when batting against England scoring 91*. With this he shares the record of becoming the fastest player along with Australia’s Jack Gregory and England’s Ian Botham, who also took 11 Tests to reach the mark of completing the all-round double of 500 runs and 50 wickets. Incidentally the quickest Indian to reach 500 runs and 50 wickets before Ashwin was Salim Durani, who did so in his 14th Test, followed by Vinoo Mankad in 15 tests and Kapil Dev in 16.

Ashwin has surpassed former India captain Anil Kumble as the leading wicket-taker for India in a four-Test series. Ashwin claimed his 28th wicket of Border-Gavaskar Trophy (2012–13) at the Feroz Shah Kotla, New Delhi. The previous record of 27 had been achieved by Kumble against Australia too, during the 2004–05 edition of the Border-Gavaskar Trophy. Ashwin and Rohit Sharma together put on a record 7th partnership of 280 Runs for India in the first test against West Indies.